Indeed, the child rape argument is the anti-Calvinist's equivalent to Godwin's Law in debates. Sigh.

Trying to get God off the hook, as it were, by claiming God did not know what His creatures would do (open theism) or that God gives man libertarian free will only makes the situation more dire. Apparently God is either impotent (cannot see the future) or able, but unwilling to intervene (corridors of time foreknowledge argument) to prevent meaningless evil acts.

These tactics make good fodder for appealing to the hoi polloi, but they illustrate the shallowness of the anti-Calvinist's unstated assumptions. Remind these proponents that God, having a sufficiently moral purpose for evil, wills righteously what men do wickedly.